The role of genetic factors in the etiology of adult onset periodontal disease and dental caries is largely unknown. This deficiency is, in part, due to lack of available family data for genetic analysis, as well as an intrinsic difficulty in analyzing common dental diseases. Both disorders pose considerable burden on the resources of the individual and society. This study is designed to collect family data on periodontal disease and dental caries in order to determine the degree of genetic control over these conditions. The specific aims are: (1) to study the familial aggregation of several measures of periodontal disease and dental caries in families; (2) to estimate the familial correlations for both periodontal indices and dental caries while simultaneously adjusting for age, sex, and other important covariates; (3) to estimate the proportion of variability in these measures which could be attributable to genetic factors from these family data. Probands and their families will be examined for periodontal disease and dental caries using standard measures. Analytical methods include the use of common summary statistics, as well as a general linear model with intraclass correlation, the conditional logistic regression model to measure association for binary traits, and variance components models. The results of this study will increase our understanding of the possible genetic mechanisms which contribute to overall dental health and could aid in targeting preventive dental care to family members who are at highest risk.